Heteroleptic Copper(II) Complexes Containing an Anthraquinone and a Phenanthroline as Synthetic Nucleases and Potential Anticancer Agents

Two ternary copper(II) complexes with an anthraquinone and a N,N-heterocyclic donor, [Cu(dmp)(L)(H2O)](ClO4) (1), [Cu(bpy)(L)(dmso)](ClO4) (2), in which dmp = 2,9-dimethyl-1,10-phenanthroline, bpy = 2,2′-bipyridine, and HL = 1-hydroxyanthracene-9,10-dione were synthesized and fully characterized by conductivity, elemental, and spectral analyses (FTIR and UV-Vis; EPR and ESI-MS). The structure of 1 reveals that Cu(II) is bound to two oxygens of L, two nitrogens of dmp, and a molecule of water in the fifth position. In complex 2.1, Cu(II) is also pentacoordinated with an O-bonded dmso in the axial position. The presence of the heteroleptic complexes in solution was evidenced by ESI-MS, EPR in dmso solution and UV-Vis spectrophotometry. All complexes bind to CT-DNA with affinity constants of approximately 104. Complex 2 can nick plasmid DNA but no cleavage was performed by complex 1. The investigation of DNA interactions by spectrofluorimetry using ethidium bromide (EB) showed that it was displaced from DNA sites by the addition of the complexes. The complexes inhibited the growth of chronic myelogenous leukemia and human squamous carcinoma cells with low IC50 values, complex 1 being the most effective.